The pipeline portion laid on the bottom of the trench does not always conform with project specifications, and, more specifically, varies in depth independently of variations in the depth of the bed of the body of water. This is a potentially serious problem that may result in severe mechanical stress when the pipeline is subjected to in-service temperature variations caused by weather or the fluid flowing along it.
Variations in the depth of the pipeline also result in shallow coverage and, hence, poor protection of the pipeline against scouring.